Process of coating web material



H. R. HARRIGAN PROCESS 0F GOATING WEB MATERIAL Aug. 18, 1942.

F'iled Oct. 25, 1939 ATTORNEY Aug. 18, 1942.' H. R. HARRIGAN' 2,293,690

--PHOCESS 0F COATING WEB MATERIAL Filed Oct. 25, 1939 5 Shees-Sheet 3 :LE- 7 J0 L HYVENTOR.

@L 3fm/L5M, BY

dre TTOIYQIYEY -U8- 18, 1942 Y H. R. HARRIGAN 2,293,690

FROCESS 0F COATING WEB MATERIAL i Filed 061;. 25, 1939 5 Sheets-Sheet 4 INVENTOR ATTORNEY Aug. 18', 1942. H. R. HARRIGAN PROCESS OF COATING WEB MATERIAL Filed oct. 25, 195s 5 sheets-sheet 5 :zr E1- 1 E Patented Aug. 18,` 1942 ENT omet s claims. (ci. 111-111) My invention relates to a process for coating web material witha film of ink which is uniform in character for producing a' smooth surface on the web material.-

' One of the objectsof myinventionls to pro-,- Vvide. a method of coating web material by which a uniform and continuous nlm of vink may be applied to the'web of material in predetermined --arrangement for insuring a uniform product in large quantity production.

VAnother object of my invention is to provide `a process of coating web material by use of an engraved roller havingpreformed pockets of uniform 2size providing carriers for ink from which a regulated coating of ink may be applied to the web of material through the intermediary of resilient surface off-set roller.

Still another object of my invention is to provide applying continuous and uniform films of ink to web material in which ink is applied to a roller' having a multiplicity of recesses in the surface thereof serving as carriers for the ink and from which excess ink is struck ofi to enable a continuous and uniform lm of ink to be appliedthroughan intermediate off-set roller to web material.

A further object of my invention is to provide 'a method of delivering a preformed lm of ink to web material which is advancing at the same speed at which the web is travelling lfor insuring a uniform application of the lm to the web material.

A still further object of my invention is to provide a method ofV coating web material by which ink may be delivered to a distributing roller and transferred to an o-set roller for impressing a continuous and uniform film of ink upon web material where provision is made for positively driving the ink distributing roller, the off-set roller and the bed roll all at the same peripheral speed. l

A further object of my invention is to provide a method of applying a uniform film of ink to web material in which an o-set resilient roller lis employed to coat the web material and wherein the off-set resilient roller is in turn supplied uniform continuous film to the web material.

Another object of my invention is to provide a vdistributing roller in coaction with a transfer f roller, the distributing roller containingpunlformly distributed recesses in the surface thereof y, forming containers for ink which coact with leveling means for insuring the removal of(` `excess ink and enabling the transfer of a uniform lm of ink from the distributing roller to the transfer roller for subsequentimpression upon web material in such manner that existing differences in thickness of the ink released from the recesses are equalized by merging 'of one portion of the ink film with an adjacent portion thereof to provide a continuous and.y uniform iilmlof ink on the web material. p

A further object of my invention is to provide a method of coating web material employinga distributing roller in `coaction with an ofset roller inengagement withweb material passing over a bed roll, preformed recesses for ink being arrangedin parallel spiralpaths around the surface of the distributing roller for delivering a uniform and continuous film of ink to the olf-set roller for impression upon the web material passing over the bed roll while maintaining substantially uniform wear between the surfaces of the `tion of myV invention in the printing of paper;

Fig. 2 is an enlarged side elevational-view of a fragmentary portion of the mechanism represented in Fig. 1 showing the method of control- A ling, the thickness of the film of ink which is impressed upon the paper sheet material; Fig. 3 is a fragmentary view illustrating a modified form of regulating the impression of ink upon the web material; Fig. 4 is a side elevational view partially broken away and illustrated in section showing the distributing roller employed in the method of my invention for regulating the quantity ofink supplied to the transfer rol1er;' Fig. 5 isa fragmentary view of the surface of the distributing roller greatly magnified to illustrate the ink receiving receptacles in the surface of the roller; Fig. 6 is a cross sectional view taken on line 6--6 of Fig. 5; Fig. 'l 'is a perspective view of a fragmentary portion of the distributing roller employed in the method of my invention; Fig. 8 is a schematic view 1 showing the distributing a method for coating web material byremploying roller, the transfer roller and a bed roll illustrat-A ing in magnified section the manner of regulating the thickness of the film of ink which is applied to the web passing over the bed roll; Fig. 9 is a fragmentary perspective view showing a further method of impressing a regulated film of ink upon web material in accordance with my invention; Fig. 10 schematically illustrates the application of my inventionto a paper machine in which paper is passed around a pair of bed rolls and a uniform film of ink supplied to opposite sides of the web of paper; Fig. 11 is a fragmentary view of a modified method of impressing a uniform film of ink upon opposite sides of a web of paper passing over a pair of bed rolls; Fig. 12 is a schematic view illustrating the manner of accurately :regulating the thickness of the iilm of ink applied to 'a web of paper according to the method of my invention; Figs. 13 and 14 are theoretical views showing by comparison the advantages obtainable by the spiral arrangement of recesses on the surface of the distributing roller coacting with an oil-set transfer roller by which uniform wear and consequently uniform distribution of ink is transferred to the off-set surface of the transfer roller for subsequent impression upon the web material; Fig. 15 illustrates a further` modied arrangement of inking means for applying a film of ink to a web of paper; and Fig. 16 is an enlarged view of the ink applying system embodied in Fig. 15.

For purposes of explaining the principles of my invention, I have illustrated my invention as applied to paper making machinery in the process of making paper, but it is to be understood that my invention is generally applicable to processes of coating web material generally. The process of my invention as exemplified by the application of my invention in the coating of paper embraces the forming of the paper web and removing the excess water therefrom, printing upon the wet web by means of a roller having a resilient surface which receives its ink or color from a distributing cylinder or roller. The cylinder or roller` of my invention may be formed by the electrolytic deposition of copper on a steel cylinder to obtain a sheathing of extremely close grain. My invention is not limited to the electrolytic deposition of the sheathing, but embraces any method for obtaining a close grain metal surface which may be suitably engraved, knurled, or recessed. Any close grained metal that may be engraved, knurled or recessed is suflicient to meet the requirements of my invention and it is not necessary that a sheath be employed, as a hollow or solid drum may be utilized. The important essential is that the surface shall be close grained. The surface of the roller is then treated by knurling, engraving or recessing the surface of the roller in such manner that the aligned elements of the knurling, engraving or recessing extend along axes which are disposediat approximately 45 with respect to the longitudinal axis of the roller and are spiraled around the roller. 'I'he character of the knurling, engraving or recessing is important and I have found that inverted pyramid recesses formed in the` surface of the roller provide means for distributing a film of ink of uniform depth to the oil-set roller for delivery to the web 'material as it passes through the machine. The roller will uniformly distribute to the off-set roller a quantity of ink which will form a uniform film of ink that may be transferred to the web material by reason of the arrangement of a doctor which functions to strike the excess. ink from the distributing roller. The pyramid shaped pockets in the roller constitute tion, that is. an aqueous mixture or oil in water emulsion that readily adheres to the web material.

By reason of the easy release of the ink from theinverted pyramid shaped pockets and because of the measurements that are obtained by striking oiI the quantity in each pocket by flexible doctors or scrapers, the spread of Ink is obtained without the use of high pressure. Consequently deflection is of minor importance with the process of my invention which permits the effective use of the invention on wide machines and with smaller and lighter parts. There must be a sumcient volume of ink to enable the ink to merge into a solid film of uniform depth on the paper. I have found the inverted pyramids highly successful in obtaining quick release of the ink and there is less tendency foxl the ink to remain in the pockets. The pockets l are relatively large and the space between the pockets relatively small and the tendency of the ink to flow into a uniform film is considerably increased. The construction .of the distributing roller and the ilexible doctor which coacts therewith are such that any irregularities or distortion in the surface of the distributing roller or misalignment thereof do not cause 'any defect in the transfer of ink to the paper. The inverted pyramids forming the ink receiving receptacles provide the best method of retaining a predetermined and measured quantity of ink that is leveled and impressed on the off-set roller, thereby producing a uniform level of ink on the web material.

Referring to the drawings in more detail, reference character I indicates the wet web of paper as it passes through the paper making machine and passes over guide roller 2 through the bed the web is carried out in accordance with my invention. 'I'he assembly of rollers 'l comprises sets of bed rolls 8, 9, III and II around which the paper web I passes in a moist state, subject only to the initial drying by passage through drier rolls 5. Coating is effected on both sides of the web. I by accurately aligned coating mechanism which I have illustrated more clearly in Fig. 2. The coating mechanism is associated with each of the bed rolls 8, 9, I8 and I I as shown in Fig. 1. The off-set roller which coacts with bed roll 8 is indicated at I2 receiving ink from distributing roller Il constructed with recessed pockets therein which are filled with ink from a suitable ink supply designated generally at I5 and the recesses leveled o by the coaction of the doctor I6 with the surface of roller I4. Similarly, ink is supplied to off-set roller I1 coacting with bed roll 8 through distributing roller I8 having recesses in the surface thereof which are continuously supplied with ink from the ink supply designated generally at I8 which is leveled in the recesses in the surface of distributing roller I8 by c'oacting doctor 20.

Referring to Fig. 2, the coating mechanism will be understood more clearly as comprising sets of associated and horizontally or vertically adjustable supports or carriers for the several rollers. The frame of the machine is indicated for example generally at 2| which serves as a carrier for transversely adjustable supportl 22. The support 22 is provided at one side thereof with a toothed rack 23 which is engageable by a pinion 24 carried on a shaft journalled with respect to frame 2| and manually controllable by a hand wheel 25 by which the entire assembly of the distributing and off-set rollers may be advanced or retracted with respect to the aligned bed rolls. The o-set roller I2 is journalled in adjustable carrier 26 which may be advanced or retracted with respect to bed roll 8 by means of adjusting screw 21 which engages screw threads in carrier 26 and passes freely through the up-standing lug on support 22 as indicated at 22a and which may be rotatably adjusted by head 24 engageable by a suitable wrench or tool. The carrier 26 is reciprocative with respect to carrier 22 by adjustment under control of screw 21. Similarly, carrier 28 in which there is journalledthe distributing roller I4, is also adjustable on carrier 26. This adjustment is effected by rotating screw 29 which passes freely through up-standing lug 3| on carrier 26 by gripping the wrench engaging The ink which is employed in the system of my invention is an aqueous mixture or oil in waterv emulsion which does not have the tendency of coalescing in the pockets in the surface of the' distributing roller .but is fluid enough to ll the pockets and yet not suiciently uid to flood the doctor, The ink is sufllciently viscous to maintain the conical pattern imparted thereto bythe v inverted conical lrecesses as the ink is delivered to the off-set" roller and yet suillciently plastic to merge into a layer when applied to the wet web material by a process of revolution and the settling of the particles of ink into a uniform layer or film. That is to say, the ink possesses a high degree of viscosity, surface tension and density.

The flowing properties of the ink are such that the ink will flow a substantial distance before the vehicle is carefully selected. I have used inks head 30 thereof and rotating screw 29 in screw threads formed in carrier 28. Thus the distributing roller I4 may be independently adjusted in spacial relation Ito olf-set roller I2, while off-set roller I2 is also independently adjustable with respect to the web of material which passes over press roll 8. I have shown the doctor I6 coacting with the recessed surface of distributing roller I4. For the purpose of regulating the film of ink transferred by roller I4 to the off-set roller I2 and impressed upon the web of paper, I mount the doctor I6 ina special form of carrier shown at 32 from which 1t may be readily removed or replaced by means of set screws 33. The carrier 32 includes an arm 32a which is connected through a spring 32h with an up-standing lug 34 on carrier 28. The carrier 32 is supported on movable member 35 which may be advanced or retracted on screw 36 by adjusting the head 31 by means of a suitable wrench. Adjustment of carrier 32 thus controls the adjustment of doctor I6 with the surface of distributing roller I4 controlling the amount of ink which is delivered to the recesses in the surface of the distributing roller I4 and the amount of ink that is struck off at the extremities of the recesses. The ink is supplied through a reservoir 38 supported with respect to movable block 35 through the support indicated at 39 for delivering through spout 40 the required amount of ink which I have represented as controlled at I5 over the doctor I6 for delivery to the recessed pockets in distributing roller I4. A tray 4| is provided beneath the wiping edge of the doctor I6 and the ink recovered for reuse through pipe line 42. Similar parts are provided for adjustably mounting distributing roller I8 and olf-set roller I1. I have designated corresponding parts by similar characters primed to distinguish the characters from the characters previously used in association with the assembly involving distributing roller I4 and off-set roller I2. Similar assemblies are associated with bed rolls I0 and II shown in Fig. l. The paper after passing through the assemblies as described, passes to the driers represented generally at 43 and under guide roller 44 through the calender rolls 45.

containing 33% solids which were found to render the process inoperative, whereas ink containing 66% of solids enabled the process to work very well. The viscosity in general should fall within limits of 500 and 1000 centipoises. The principal characteristic of the ink is that because of the water soluble properties of the ink, the ink will readily mix with and be absorbed by thewet i to the surface of distributing roller 50. Doctor 5| strikes or levels'oi excess ink from the surface of roll and returns the excess ink to the trough 41. Distributing roller 50 makes surface contact with olf-set roller 52 to which a uniform ilm of ink is supplied and which is transferred to the web material I. It will be understood that the peripheral speed of the inking roller, the dis- I have illustrated in Fig. 3

tributipgv roller, the off-set roller and the assoy ciated bed ,roller is the same. Such uniform y speed may be effected througha system of gears, i

chain and sprockets, bits or other suitable means. The important characteristic of the assembly is that the peripheral speedsbe uniform and that the inking, distributing and off-set rollers and the bed roll each be positively driven. The particular mechanism by which this is accomplished may be varied in detail.

Referring to Fig. 4, I have. illustrated the construction of one of the distributing rollers represented by reference characters 50 as comprising a hollow steel drum 53 carrying the electrolytically disposed close grained metal sheath 64, the surface of which is recessed in a spiral,l

pattern running at approximately 45 with respect to the longitudinal axis of the miler as indicated at 55. The ends of the drum 53 have plugs 56 set therein from which extend the shaft memlbers 51 for driving the'roller.

Figs. 5 and'6 illustrate on a magnified scale, the preformed shape ofthe pocket or recesses in the surface of the distributing roller 50. Recesses are knurled, vengraved or otherwise formed in the surface 5I)v in rows disposed approximately 45 with respect to thel longitudinal axis of the ed pyramids or cones shown'atji. The ape; of the pyramids or cones extend radially downward toward the center of the distributing roller and.

are rounded to readily release the ink and prevent accumulation of the ink inthe pockets.

Thevwalls of the inverted pyramids or cones are4 able that this 'surface band be narrow in order that the Vmaxirrnim amount of ink may be distributed through the open bases of the pockets 59 and also to reduce to a large degree the amount of surface friction established by the inking roller,`the doctor and the off-set roller in contacting thesurface of the distributing roller. This will be clear by reference to Figs. 13 and 14. In Fig. 13 1 have shown the result which would beobtained in using a distributing roller having recesses 5I therein which extend around the surface of the roller in paths normal to the axis of the roller, separated by narrow surface bands 59', Lwhile in Fig. 14 I have shown the arrangement of recesses 5l separated by spiral surface v bands 59 on the surface of the distributing roller` r in accordance with my invention. 'Ihe ink which accumulates inthe recesses 59 has been shown in Fig. 13 represented bythe successive darkened portions of the strip-like element separated by the light portions representing the surface of represent elements extending longitudinally of the off-set roller which would normally contact the surface of thedistributing roller. With the recessesarranged as shown in Fig. 13. it will be apparent that very substantial surface friction withinherent wearing occurs along the element i2 on the band width surface of the distributing roller. [Also it will be observed that for the entire longitudinal strip I! there is no supply of ink for that corresponding element of the offset roller. On the other hand, reference to the element of my invention as illustrated in Fig. 14 will show that for strip elements f and l2' only a relatively small part ofsuch elements extend across the surface bands 59 at any time. Moreover. within thevelements Il' and I!" thereis a1- ways a substantial supply of ink for the correspending elements of the off-set roller. Thus the spiral arrangement of pockets insure minimum wear of the distributing roller and maximumsupply of ink to the oiI-set roller for any longitudinal element of the distributing roller.

The perspective view of the distributingv roller shown in Fig.y 'l will make clear the spiral arrangement of pockets 59 in the surface of the distributing roller 50 andthe manner in which the close grained sheath I4 is carried by the hollow steel drum 53 and subject to renewal thereon.

In Fig. 8 I have shown a theoretical view somewhat out of proportion for the purpose of theoretically illustrating the manner in which a with the surface of the distributing roller-,in the course of rotation thereof. The off-set roller Il which is traveling at the same peripheral speed as the distributing roller I9 receives the ink III as represented at a and carries the ink by movement in a clockwise direction toward the web material I.y VAs heretofore noted, the viscosity,v

surface tension and densityof the ink are such that the individual charges or deposits of ink 5M merge by a resolution of forces due to gravitation and rotation as indicated at lib. 'The merging charges or deposits of ink 99a form into a lm of uniform thickness as represented at "c on the surface of web material I as bed roll! rotates as shown. 'I'he off-set roller I1 has a resilient surface indicated at Ila constituted by `a cornposition or rubber covering. This covering has a plastometer reading of approximately 120 measured with a 1A, inch ball. 'I'he pliability and resiliency of the off-set surface is such that a uniform film of ink is applied to the web material I.

In Fig. 9 I have shown in perspective view` the manner in which inking roller 48, distributing roller 50, off-setroller 52 andv bed roll 48 are driven at. the same peripheral speed. I have shown intermeshed gears 48a, 59a, 52a and 45a carried by the shafts ofthe respective rollers.

These gears have teeth which are somewhat elon-' which the inkis continuously pumped as it overl flows .from trough 41 through pipe 63 into reservoir 54- from which the ink is pumped by pump through spout 49 for return to trough 4l.

My invention is equally applicable to machines whose purpose is to coat web material independ-A ently of the machines by which the web material may be actually formed. 'Ihat is, in the case of paper I may apply a coating in accordance with the principles of my invention by a machine which is entirely independent of the paper making machine. In Figs. 10 and. l1 I have indicated two forms of suchmachines. I have shown the web material I- passing around bed rolls 9' and 9' which correspond to bed rolls 8 and 9 of Fig. 1 except that bed rolls 8' and 9' maybe mounted in an independent machine as distinguished from the paper machine schizmatically shown in Fig. l. Ink delivered through spout 40 is accumulated at I5 and applied to the A surface ofY distributing roller I4 and equalized thereon by the coaction of doctor I5 with roller I4. The ink is then applied through off-set roller I2 to the web material I coacting with bed roll 9'. The yopposite-side of the web material is coated by ink delivered through spout 40' and accumulated at I9 for covering the surface of distributing roller I9 with which doctor 20 coacts. A film of ink is thus applied to off-set roller Il and impressed upon web material I.

In Fig. ll'I have shown web material Ifpassing around bed rolls 66 and 51 with each of which there is associateda coating mechanism. On'- set roller 69 applies a uniform film of ink to web material I by virtue of the ink coating delivered by distributing roller 69 which is supplied with ink from inking roller 'II in coaction with y In Fig. l0 i trough 12. The opposite side' of the web material I is coated with a nlm of ink by operation of oil-set roller 68', distributing rollerV 69' and inking roller 1I coacting with doctor 19'. Inking roller 1I' receives its supply of ink from trough 12'. Thus it will be seenthat the ink may be delivered to the distributing roller in substantially vertical' planes while the ink is transferred to the web material in a horizontal plane.

In Fig. 12 I have shown an enlarged theoretical view of the arrangement of inking roller 48, distributing roller 50 and ofi-set roller 52 for-applying a uniform film of ink upwardly against web material I operating against bed roll 46. It will be observed that ink delivered to k trough 41 through spout 49 forms a pool 11 in which inking roller 48 is submerged. The lnk is picked up by rotation of the inking roller as indicated at 11a and is delivered to the recesses or pockets in distributing roller 50 as indicated at 11b. Excess ink is struck oil` -from the pockets 11b by coaction of doctor 5I with the surface of the distributing roller, the excess being returned as indicated at 11c to the=pool of lnk 11 in trough 41.

Doctor 5I is mounted in carrier 13 pivotally mounted at 14 from which arm 15 projects. Arm 15 is continuously urged by spring 16'in,a direction which causes doctor 5I to engage the surface of distributing roller 50 and strike off the excess ink to equalize the ink retained in the recesses or pockets as represented at 11d. 'I'he off-set roller 52 receives the charges or deposits of ink from the pockets in the distributing roller by adherence of the ink to the resilient surface 52a as indicated at 11e. By virtue of the forces of gravitation combined with the rotation of the offset roller 52, the ink due to its viscosity, surface tension and density merges as represented at 1'lf and is applied in a substantially uniform film at 11g to the web material I. It will be understood that the arrangement illustrated in Fig. 12 is considerably magnied in order to clearly bring out the method of securing the coating of uniform thickness on the web material in accordance with the principles of my invention.

I have hereinbefore described the advantages of extending the recesses or pockets 58 in a spiral path-as illustrated in Fig. 14 as distinguished from paths normal to the axis of the distributing roller as illustrated in Fig. 13 whereby frictional wear is reduced and a larger quantity and more uniform distribution of ink is secured.

In Fig. 15 I have illustrated a further method of applying a lm of uniform thickness to web material. For purposes of illustrating my invention, I have shown the method in Fig. 15 as ap plied to a paper making machine having frame 18 with sets of drier rollers 19 over which the paper I moves. The paper is guided around driers 89 and 8| where it is coated in accordance with the principles of myinvention by coating mechanism which is arranged at approximately 45 with respect to the longitudinal axis of driers 89 and 8|. One side of the web material I is coated by the mechanism represented generally at 82 while the opposite side of the web material is coated, printed and/or decorated by the mechanism illustrated at 83. 'Ihe web material after leaving driers 85 passes around guide roller 84 to the rollers 80 and 8| where it is coated and thence to the additional driers represented generally at 19. The coating mechanism illustrated nism illustrated in Fig. 2 except that the mechanism is mounted at approximately 45 with respect to the longitudinal axes of the driers 89 and 8|. As shown in Fig. 16, the frame 2| of mechanism 83 and frame 2|' of mechanism 82 extend approximately at 45 with respect to the axes of driers 8| and 89 respectively. Similar parts of mechanism 88 have been indicated by primed characters in describing mechanism 82. The mechanisms, while generally the same as that illustrated by corresponding -reference characters in Fig. 2, differ to the extent that the adjustable -'support for the doctor I6 is so arranged with respect to the distributing roller I4 that excess lnk accumulated by hiking roller 86 from trough 81 is removed from the surface of distributing roller I4 and returned to the trough 81. The arrangement of the inking roller and trough7 in the mechanism shown at 82 has been designated at 86' and 81' respectively. 'I'he screw 36 engages adjustable member 88 which supports the carrier 89 for the doctor I6. Carrier-89 is provided with a connecting means 88 for spring 99 which connects with the arm 9| of carrier 28', thereby continuously urging doctor I6 into cooperative contact with the surface of distributing roller I4. Because ofthe -fact that web material is traveling clockwise around drier 80 and counterclockwise around drier 8|, the direction of rotation is oppsite in the respective mechanisms. I therefore iind it desirable to mount the support for the doctor I6 in mechanism 83 above the distributing Vroller and the support for the doctor I6' in mechanism 82 below the distributing roller so that the doctor coacts at all times in removing excess ink from the surface of the distributing roller in each arrangement. 'I'he manner of adjustingv the spaclal relation of the distributing roller I4. the oil-set roller I2 and the doctor I6 under control of hand wheel 25 is the-same as the arrangement illustrated in Fig. 2 and corresponding parts have been indicated by similar or primed reference characters in each case. In the mechanism shown at 82, the` screw 36 is journaled in members 92 and 93 which project downwardly from carrier 28' through slots in carrier 26', support 22', and frame 2l. The adjustable v screw 36' engages member 94 having a laterally at 82 and 83 is generally similar to the mecha- 75 extending projection 95 thereon from which a vertical member 96 extends forming a journal 91 for the doctor I6' which is supported in carrier 98. An arm 99 extends from carrier 98 and is connected through spring |00 with laterally projecting member 95 whereby doctor I6 is constantly urged into contact with the surface of distributing roller I 4'. The spacial relation of off-set roller I2 and distributing roller I4 as well as doctor I 6' may be readily controlled by a combination of aisijustments including hand wheel 25' and screw will be understood that in the arrangement of the mechanism illustrated at 82, the support for the doctor extends downwardly, whereas in the arrangement shown at 83 the support for the doctor extends upwardly. However, the operating mechanism is similar in each instance and the same adjustments may be effected.

I have described my invention in certain preferred embodiments but I realize that modifications may be made. I do not intend any limitations upon my invention other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. The method of coating a web of paper. whicl` comprises owing an excess of a highly viscous aqueous coating composition having considerably in excess of 33% solids content onto a rotating surface having regularly arranged and uniformly sized pits over an area thereof at least the width of the web of paper to be coated, doctoringv away the excess of said coating composition to leave substantially equal volumes of said composition in said pits, rotating said pitted surface into contact with a non-absorbent resilient surface to transfer thereto ythe coating composition from said pits, the viscosity and other characteristics of said coating composition being such that said coating composition is deposited from said pits on said resilient surface as mounds that tend to coalesce and level off into a film `of substantially uniform thickness over said resilient surface, allowing the mounds to coalesce on the resilient surface, bringing the web to be coated into contact with said film formed on said resilient surface, subjecting the portion of said web in contact with said film to rolling pressure to cause said film to uniformly and continuously coat said web surface and to cause the solids content of said film to be pressed onto and compacted with the surface fibers of said web to be made an integral part thereof, and drying the thus coated web.

2. The method of coating paper, which comprises advancing a wet web of paper, flowing an aqueous surfacing mixture having considerably in excess of 33% solids content onto a rotating lm forming intaglio surface dimensionally pitted over an area at least the width of said web for substantially uniform, volumetric measurement transferring said surfacing mixture from said pitted surface to a resilient transfer surface and forming thereon a continuous film of predetermined uniform thickness by the mutual action of the forces of said mixture and said resilient surface, bringing the surface of the web throughout its entire width into contact with said film while on said resilient transfer surface, subjecting the portion of the web in contact with said film to rolling contact pressure to cause the film to uniformly coat the entire surface of said web and tocause the solids content thereof to be pressed onto and compacted with the surface fibers of said web to be made an integral part thereof as said film is applied thereto, and drying the thus coated web.

3. The method of coating a web of paper, which comprises flowing an excess of a highly viscous aqueous coating composition having a minimum viscosity of about 500 centipoises and having considerably in excess of 33% solids content onto a rotating surface having regularly arranged and uniformly sized pits over an area thereof at least the width of the web of paper to be coated, doctoring away the excess of said coating composition to leave substantially equal volumes of said composition in said pits, rotating said pitted surface into contact with a non-absorbent resilient surface to transfer thereto the coating compostion from said pits, the viscosity and other characteristics of said coating composition being such that said coating composition is deposited from said pits on said resilient surface as mounds that tend to coalesce into a film over said resilient surface, allowing coalescence of said mounds on said resilient surface to take place, bringing the web to be coated into contact with said coating composition on said resilient surface, subjecting the portion of said web in contact with said coating composition to rolling pressure to cause said composition to uniformly and continuously coat said web surface and to cause the solids content of said composition to be pressed onto and be compacted with the surface fibers of said web and drying the thus coated web.

HERMAN R. HARRIGAN. 

